I know vertical foregrips on pistols make them into an AOW. The only thing I do not understand is how is a Thompson 1927a5 not an AOW. It had a vertical foregrip, but it was just classified as a pistol, whereas, say, an sp89 had the vertical grip deleted in favor of a smooth horizontal unit to become a pistol instead of AOW.

tommy gun was before NFA, you could walk down to your local hardware store and buy a short barreld full auto rifle just like you would buy a shovel or a hammerback then it was ok to have sholder stocks on pistols. very short barrel shotguns... people have to abuse it before they start regulateing it

I am not talking about a Thompson Submachine Gun, I am talking about a semi automatic Thompson 1927a5 pistol. Basically it is the semi auto carbine with no buttstock and a 13" barrel. It was offered for sale up to '94 IIRC.